Question

The number of circular pipes with an inside diameter of 1cm which will carry the same amount of water as a pipe with an inside diameter of 8cm is a) 16 b) 36 c) 49 d) 64

Answer 1

The number of circular pipes required is (d) 64.

Assuming length of pipes to be same.

Volume of shorter pipes will be equal to volume of longer pipe.

Thus, A1*L1 = A2*L2

L1=L2.

A=πr²

Let the number of pipes required is n.

So, Nr1²= r2²

N * (1/2)² = (8/2)²

N*0.5²= 4²

N= 16/0.25

N= 64.